One thing I love that I can see in the Early Access Demo is that you guys are keeping things interesting, without becoming cheesy like many developers do while thinking up new 'Creatures'.
Being a person that greatly criticizes Flora and Fauna in games such as this, one thing I always see lacking is the invention of completely new evolutionary chains of species. They always take from what we have here; Plants, Insects, Amphibians, Reptiles, Mammals, Chordates, Invertebrates; etc. However, there is a high chance that life on other planets will take completely different evolutionary route. Chances are we won't see Woody Trees with Roots that dig deep into the ground, and leaves that photosynthesis, or Insects that live short life cycles, but breed quickly and numerously to make up for their short life cycle. Yeah, we might see some similarities, but chances are that the core of the creatures are going to be completely different (Which you guys have picked up on, and which I love the results of so far).
This of course is a major challenge, and you can clearly see it by looking up any concept art depicting "Alien Life", they always have things that we see here on earth; if its landscape they'll have trees (Or some sort of woody material that greatly resembles a tree), with life forms that greatly depict creatures on earth ( To the point that if we discovered them as fossil remains, we'd classify them as a ascendant of current lifeforms on earth.
It can also be very time consuming, as you pretty much have to create and imagine a completely new cycle of life, that is totally different from what we are use to - while keeping it totally believable.
I'll think on it here and there, and see if I can present you with some ideas

.